Calgary’s Excessive Vehicle Noise Bylaw and it’s Flawed CreationPosted by: Shelton Kwan onJune 1st, 2012
John Mar’s statement is technically correct, unfortunately, the measurement methods by Calgary Bylaw are completely wrong. We touched on why the new bylaw is flawed in our post about the Noise Snare, where our Mercedes Benz C63 AMG Black Series failed the bylaw’s definition of objectionable noise. With the help of curious Beyond members in the discussions thread, we were able to figure out why our new and completely stock vehicle was able to fail the test so badly. Let’s start from the top.
It all started with City Council wanting to control objectionable noise, mainly, from motorcycles in areas such as 17th Ave SW, where the roar of their loud pipes makes it difficult to carry conversations on the street. In the City Council meeting on May 18th, 2011, a report was tabled that claims:
Vehicles that are imported or manufactured in Canada are required to meet federal guidelines for noise emissions. The highest permitted exterior noise level for a new vehicle is 84 decibels. These levels will increase marginally as the vehicle experiences normal operating wear and tear or more significantly, if the vehicle is not maintained or is modified from the original manufacturer’s equipment to deliberately emit higher noise levels.
The Traffic Bylaw 26M96 would be amended to make it an offence for any vehicle to exceed the maximum decibel limit. It is recommended that the decibel limit be set above the maximum level specified at time of manufacture to allow for vehicle noise levels increasing with normal wear and tear.
A number much higher than the federal standard of 84db was chosen for margin of error as well as wear and tear causing higher noise levels in older vehicles. So with that, the city approved a new bylaw amendment to 26M96, which added a new definition for objectionable noise. Section 2(1)(y.1)(vii) states:
(y.1) “objectionable noise” means any sound caused by or emanating from a motor vehicle that annoys or disturbs humans or endangers the health and safety of humans and includes:
(vii) noise measured at 96 decibels (dBA) or more as measured by a sound pressure level meter at any point of reception.
Reference: City of Calgary Bylaw Number 26M96
Unfortunately, the way city council came up with the db rating is incorrect. We have to look at the federal Motor Vehicle Safety Act, which is what City Council referred to in the May 18th, 2011 meeting. The exterior sound level is defined in 2(b)(iii) for passenger cars of the Motor Vehicle Safety Regulations Schedule V.1:
(iii) SAE Recommended Practice J986, Sound Level for Passenger Cars and Light Trucks (August 1994), or SAE Standard J1470, Measurement of Noise Emitted by Accelerating Highway Vehicles (March 1992), the exterior sound level does not exceed 80 dBA when a value of 2 dBA is subtracted from the highest average sound level recorded during the test, in the case of a passenger car regardless of its GVWR or any other vehicle with a GVWR of 2 722 kg or less.
Reference: Motor Vehicle Safety Regulations
Where did the 84db in the city council meeting come from? A little further down in section 4(a)(iii), 84db is mentioned for trucks with a GVWR of more than 4536kg, which is the highest noise level allowed in Schedule V.1:
(iii) 84 dBA, in the case of a vehicle with an engine that produces 150 kW or more
With that being said, 2(b)(iii) defines the test criteria in SAE Recommended Practice J986. It’s a very detailed document of the testing procedures on measuring the sound level for the federal test. Section 4.5.1 covers the actual test procedure:
4.5.1 For this test, the vehicle shall approach the measurement area along the vehicle path with the vehicle speed stabilized at 48 km/h ± 1.2 km/h. The highest-numerical-ratio transmission gear shall be used that will result in the front of the vehicle reaching or passing the entry point of the end zone before rated engine speed is attained. It is recommended that the approach speed be held constant for a distance of at least 7.5 m prior to reaching the start point.
When the front of the vehicle reaches the start point ± 1.5 m, the throttle control shall be fully depressed as rapidly as possible and the vehicle allowed to accelerate until the engine reaches rated engine speed. The test run is then terminated and the throttle control may be released.
Reference: SAE J986
The test is a full throttle test in the highest numerical ratio (which means the lowest gear) possible at the test speed to generate as much noise as possible starting at 48km/h. I won’t quote the rest of section 4, you can read from the reference document yourself, but every point is made to ensure the most noise is made.
Now comes the fun part, where City Council made their mistakes. In SAE J986, the measurement distance is defined in 7.5:
7.5 The microphone shall be located 15m from the centerline of the vehicle path and 1.2 m above the ground plane. The reference axis of the microphone shall lie in the vertical plane containing the perpendicular to the vehicle path through the microphone location.
Looking back at how City Council approved this bylaw, we find that it was approved based on a consultant’s report that the noise snare is accurate. The consultant used a 10m distance for the test, which is inconsistent with SAE J986 testing standards.
The positions for the measurements were in line with the noise snare microphone and perpendicular to the road, and 10 meters back from the center of the closest lane to the noise snare microphone. The microphones were approximately 1.5 meters off the ground.
Reference: Community Services & Protective Services Department Report to
The SPC on Land Use, Planning and Transportation LPT2011-100
Reference: Patching Associates Acoustical Engineering Consultant’s Report
Reference: Vehicle Noise Samples
The city also performed their own tests in 2010, with even more inaccuracies.
Sound monitoring took place on 29 September 2010. All sound levels were recorded
using dBA scale. Distances from edge of the road varied from curb to 2.0 meters back.
So the million dollar question, where did the 96db limit come from? Looking at the General Noise Readings report, a car with a modified muffler registered 96db (measured at 2m). From the Independant Consultant’s Vehicle Noise Sample report, 96db seems to be a good number to use as only 15 out of 11347 cars failed the test (0.13%). Problem here is that the Consultant’s report was measured at 10m, and the number will be much higher if the 2m distance typical in the noise snare deployment on the side of the road is used instead. Using some quick math, if 96db at 2m is equivialent to 82db at 10m, and using the results from the report, the number of cars failed jumps from 15 to 443, or a whopping 4% failure rate. That’s $85,600 in additional ticket revenue.
Unfortunately, in our bylaw amendment, it’s even more vague. It states that the level is recorded “at any point of reception”, with no distance from the source of the vehicle noise to the microphone defined. The test at the Noise Snare open house was done with the microphone located approximately 1m away from the vehicle on the side of the road, hence the values read so much higher, and why our Mercedes Benz failed the test even at part throttle. In fact, the reading was so high that under braking, the Mercedes Benz registered a 90db reading, far higher than the federal government’s tolerance for noise level under their test at full throttle (80db + 2db subtraction). Our full throttle run mimics the government test closely, and it registered a 102db reading, well above the federal standards.
If we run those numbers through a sound distance calculator, our highest value of 102db at 1m is equivilent to 78.48db at 15m specified in SAE J986, which is well within the federal noise limit. That’s a difference of 23.5db. For comparison, a difference of 20db equals 4x as loud to the human ear, or 10x higher sound pressure levels. Quite a huge error in measurement when the bylaw itself is based on the federal noise limits for vehicles certified for Canada.
What have we learned here? City Council made mistakes, and they’re only human. They made an error from a report provided by Administration of a 84db limit without looking into how this value was measured by the federal government. Not enough due diligence on this matter, and the bylaw amendment was passed all based on a faulty report. The bylaw needs to be corrected, and a proper distance of measurement must be defined, otherwise noise levels much higher will be recorded, and vehicles that pass federal standards would fail the test.
The members of Beyond were all in favor of the noise snare when it was first announced back in 2011. We trusted the city to perform due dilligence and create a bylaw that is fair, and works properly to ticket modified vehicles that are excessively loud. When the city hosted the open house to test vehicles and unmodified vehicles were failing the tests by a huge margin, that’s when red flags came up and the investigations began.
I want to thank all the members of Beyond that helped with research in the Excessive Noise Bylaw thread. Let’s hope that our hard work can drive some changes to this new bylaw amendment.